World Champion Wladimir Klitschko of Ukraine waits in the corner as referee Ernest Sharif kneels in front of challenger Francesco Pianeta and stops their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

World Champion Wladimir Klitschko of Ukraine waits in the corner as referee Ernest Sharif kneels in front of challenger Francesco Pianeta and stops their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

World Champion Wladimir Klitschko of Ukraine waits in the corner as referee Ernest Sharif stands in front of challenger Francesco Pianeta and stops their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

World Champion Wladimir Klitschko of Ukraine waits in the corner as referee Ernest Sharif stands in front of challenger Francesco Pianeta and stops their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

World Champion Wladimir Klitschko (back) of Ukraine delivers a punch to challenger Francesco Pianeta during their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

World Champion Wladimir Klitschko (back) of Ukraine delivers a punch to challenger Francesco Pianeta during their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

World Champion Wladimir Klitschko (L) of Ukraine delivers a punch to challenger Francesco Pianeta during their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

World Champion Wladimir Klitschko (L) of Ukraine delivers a punch to challenger Francesco Pianeta during their IBF IBO WBA WBO World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.

Wladimir Klitschko of Ukraine celebrates defeating Francesco Pianeta of Italy and retaining his IBF, IBO, WBA, WBO titles after their World Championship fight at SAP Arena on May 4, 2013 in Mannheim, Germany.